Foreign gene transfer into nigorobuna (Carassius auratus grandoculis)

Supercoiled and linear plasmid DNA containing the Escherichia coli beta-galactosidase gene was injected into dechorionated nigorobuna (Carassius auratus grandoculis) eggs prior to first cleavage. The survival rates in the hatching stage were 73% to 89% for injected eggs in comparison with controls (non-injected chorionated eggs). The exogenous DNA was detected by polymerase chain reaction (PCR) in all of the three-day-old larvae analyzed and in about 20% of two-year-old adult fish. Expression of the transgene was easily examined by a histochemical method using dechorionated eggs. The incidence of beta-galactosidase-positive embryos was highest in the gastrula or embryonic-body-formation stage and became low in the embryonic-body-movement stage. These results suggest the usefulness of funa (Carassius fishes) as a model fish in transgenic experiments, and the applicability of the transgenic technique to the improvement of funa as a food source.